This invention relates to vehicle brake systems, and more particularly to provisions of brake systems for reducing the risk of injury to vehicle operators from shock transmitted through a brake pedal when the vehicle is involved in a collision.
Vehicles such as automobiles, trucks, buses, and motor homes typically include a dashboard at the front of the passenger compartment, having a pneumatic or hydraulic brake booster mounted on the front of the dashboard connected by a push rod to a brake pedal mounted on a pedal bracket assembly located within the passenger compartment.
In a collision involving major frontal impact damage to a vehicle, components on the front side of the dashboard, including the power brake, are sometimes driven back toward the passenger compartment. The driver is also thrown forward for a short distance with considerable force, despite the proper use of a driver restraint system.
The combination of rearward movement of the brake booster, and forward movement of the driver can result in injury to the driver from contact with the brake pedal, or from force transmitted through the push rod to the brake pedal.
What is needed, therefore, is an improved push rod that reduces the risk of injury to the driver in a frontal collision. It is also desirable that following such a collision the push rod be configured to remain operative after the collision, and to return fully to normal operation after the collision.
Our invention provides such an improved push rod in the form of a collapsible push rod having first and second telescoping members, and retractable locking means for selectively locking the first and second members together against telescoping. During a frontal impact collision, the members telescope into one another to shorten the length of the push rod and compensate for rearward movement of the brake booster and forward movement of the driver.
The push rod may include features that allow the push rod to continue functioning while in the collapsed state.
The push rod may also include features for re-setting the retractable locking means after the collision. The push rod may also include features for returning the push rod to its normal un-telescoped length following the collision, if the push rod is not damaged in the collision.
The retractable locking means may include an electrically actuated solenoid for selectively locking and unlocking the first and second members against telescoping, in response to an electrical signal applied to the solenoid.
Our invention may also take the form of a brake apparatus or a vehicle including a push rod as disclosed herein.
The foregoing and other features and advantages of our invention are apparent from the following detailed description of exemplary embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.